540- The trick, after you have good, consistent 3s, is to not think 360, you have to think of spotting your landing only at 540. You'll probably be accustomed to spotting your landing at 3, and if you do that, youll never get that extra spin in. You have to just keep looking over your shoulder ti'll you are facing backwards. If you land at 3 and spin the rest on the ground thats the first step to sucess. After that step, go bigger and it'll come around no problem.
I can't wait for NS radio!